Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Income tax expense	$ 56,879	$ 73,082
Effective tax rate	26.00%	34.00%
Federal statutory rate	21.00%	35.00%
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	$ 16,400	$ 2,300
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	8,300
Undistributed Earnings of Foreign Subsidiaries	(4,900)	(4,100)
State income tax expense	3,800	3,400
Effective Income Tax Rate Reconciliation, Deduction, Qualified Production Activity, Amount		$ 5,900
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	15,600
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	(15,600)
Second component of tax deductible goodwill, net of tax	$ 300